From #978, operator system description and actions.
“… as pilots, that once we recognize the issue, we can stop the negative impacts by taking the trim system out of the loop.”
Recognition is paramount.

A pedantic Point; most of the discussion is about trim, whereas the device is an augmentation system which interfaces with trim as the output.
Questions for clarity; does the trim-wheel move when the MCAS is active? Is it a serial or parallel design ?
If no movement, then in piloting terms MCAS has no meaningful visual relationship with the conventional use of trim; thus the critical action is to take MCAS out of the loop not trim per se.

It is difficult to recognise the situation without first experiencing the out-of-trim force (in simulation, are simulators so equipped ?), and with demonstration, to understand the combinations of associated alerts, both visual and audio, so as not to confuse this specific situation with any other involving individual input failures.

There was no prior description provided for pilots. How about engineering / maintenance, or at least in a reasonable guide for troubleshooting.
Was the FAA aware; their flight ops, training, airworthiness (monitoring previous events), certification ?

Learning for safety; which was the initiating event; which were enabling factors - ‘holes in the cheese’
Regrettably this event has great learning potential for the industry; if only …

“...no matter how hard they try, humans can never be expected to out perform the system which bounds and constrains them. Organisational flaws will, sooner or later, defeat individual human performance.”

“Responsibility lies with those who could act but do not, it lies with those who could learn but do not and for those who evaluate it can add to their capacity to make interventions which might make all our lives the safer.”
Phillip Capper – ‘Systems safety in the wake of the cave creek disaster.’

That a critical control feature has apparently been undocumented/unavailable to the pilots flying the MAX.
As a long time software engineer to make these types of changes without notice to users is...not good. And my users were merely people sitting at desks, not flying planes.

I have to wonder about liability for Boeing here.

Does not show the article. Only a News archive.
...perhaps only available to members?
Also a google search cannot find a thing. So I guess this emergency directive is....secret? At least to the general public?

From the “Boeing Media Room”.....

“On November 6, 2018, Boeing issued an Operations Manual Bulletin (OMB) directing operators to existing flight crew procedures to address circumstances where there is erroneous input from an AOA sensor. “

Exceot for two things, the first being there is no AoA display. Second, the crew must first understand that the “existing procedures” ALSO apply to MCAS FAULT...

Trying to conflate “existing procedures” with no published link to the faulty system is dishonest and misleading.

I posted that earlier. Deleted. It is analogous to a stickpusher, but is “stickpusher light”. Sneaky input from TRIM had a material part to play in AF447.

”Partial and mysterious TRIM input in manual flight”. Close to the deck, without trained response to fault.

Liability? Boy Howdy.

it’s like they said “hey follow existing procedures” and then a couple days later it’s “oh here’s something related that we never published “

that cant be good

[QUOTE=Smott999;10308100]/QUOTE

It’s damning, and the lawyers who wrote it know exactly what is wrong with that statement. They also know almost all people will believe it exonerates Boeing. It won’t it digs them in deeper.

The AD is self explanatory.

Probably. But a less likely possibility is that replacement solved one problem but was not done correctly and created a larger one.

Why were the previous 3 flights recoverable but not this one ?

And with all the planes out there flying hundreds if not thousands of flights daily fitted with the same systems, why was this plane so far the only one exhibiting the anomaly ?

Also as an engineer , with only 2 AoAs, I’d be reluctant to make any decision based on a disagree. Perhaps a “large” disagree, but in any case, without a majority vote, asking HAL for nose-down Trim seems scary.

The AD states AoA disagree plus (in concert with) other “faults”. The key problem is that appropriate data that should have been in the Manual was missing.

One of these faults is “unable to disengage autopilot”. Which is interesting, because the mystery problem occurs only in manual flight.

in any case, the AD refers to “erroneous” AoA data. As two discrete installed systems, Independence of data sources instead of sampled together, seems an odd approach.

It may be Boeing’s idea to keep them discrete so a simple change of command would likely solve the MCAS issue. However, handing off a corrupted flight path might be worse.